#!/usr/bin/python3
import tkinter as tk
from tkinter import ttk
import sys, os, json, traceback

################################################################################
# DEFINITIONS
################################################################################

EXIT_SUCCESS=0
EXIT_ERROR=1

default_configuration = {
    "window geometry": "640x480"
}
# empty configuration by default because new values will be added while trying to load them
# this allows the IDE to load old configuration files with missing keys
configuration = {}
home_directory = os.path.expanduser("~")
config_file_path = os.path.join(home_directory, "some_ide_config.json")

def info(message):
    # print info to sys.stderr because it isn’t really output, just debug information
    print("INFO: "+str(message), file=sys.stderr)
    traceback.print_stack()

def warn(message, is_exception=False):
    print("WARNING: "+str(message), file=sys.stderr)
    if is_exception:
        traceback.print_exc()
    else:
        traceback.print_stack()

def error(message, is_exception=True, handle_gracefully=True):
    print("ERROR: "+str(message), file=sys.stderr)
    if is_exception:
        traceback.print_exc()
    else:
        traceback.print_stack()
    if handle_gracefully:
        pass
    else:
        sys.exit(EXIT_ERROR)

def get_configuration_value(key):
    if key in configuration:
        pass
    else:
        info("Requested configuration value for "+str(key)+" not in configuration. Loading from default configuration.")
        try:
            configuration[key] = default_configuration[key]
        except KeyError:
            error("Requested an invalid configuration key.")
            return None
    return configuration[key]

def set_configuration_value(key, value, save_to_disk=True):
    if not key in configuration:
        info("Writing configuration for previously unknown key "+str(key)+".")
    configuration[key]=value
    try:
        config_file = open(config_file_path, "w")
        config_file.write(json.dumps(configuration))
        config_file.close()
    except:
        error("Failed to save config file.")

# easy way to get data out of window events
class Window_Interaction_Handler:
    # constructor
    def __init__(self):
        self.__window_interactions = {}

    # add a result for an interaction event, saves results in reverse order by default, can optionally call another function
    def interact(self, name, result, reverse_order=True, additional_action=None, additional_action_parameters=()):
        if name in self.__window_interactions:
            if reverse_order:
                self.__window_interactions[name] = [result] + self.__window_interactions[name]
            else:
                self.__window_interactions[name] = self.__window_interactions[name] + [result]
        else:
            self.__window_interactions[name] = [result]

        if not additional_action==None:
            additional_action(*additional_action_parameters)

    # get first result for a given event from the list of results (newest (default) or oldest), removes the returned result from the list by default
    def get_result(self, name, remove=True):
        if name in self.__window_interactions and len(self.__window_interactions[name])>0:
            if remove:
                result = self.__window_interactions[name].pop(0)
                if len(self.__window_interactions[name])==0:
                    del self.__window_interactions[name]
                return result
            else:
                return self.__window_interactions[name][0]
        else:
            return None

    # get all results for a given event
    def get_results(self, name, clear=False):
        if name in self.__window_interactions and len(self.__window_interactions[name])>0:
            results = self.__window_interactions[name]
            if clear:
                del self.__window_interactions[name]
            return results

    # clear results for a given event
    def clear(self, name):
        if name in self.__window_interactions:
            del self.__window_interactions[name]

    # destructor
    def __del__(self):
        if len(self.__window_interactions)>0:
            warn("__window_interactions not empty upon destruction of Window_Interaction_Handler:\n"+str(self.__window_interactions))

################################################################################
# PROGRAM STARTUP
################################################################################

# read configuration
if os.path.isfile(config_file_path):
    try:
        config_file = open(config_file_path, "r")
        configuration = json.loads(config_file.read())
        config_file.close()
    except Exception:
        error("An exception occurred while trying to load the configuration.", handle_gracefully=False)
else:
    # config not found
    dialog_interaction_handler = Window_Interaction_Handler()

    dialog = tk.Tk()
    dialog.title("No configuration found")
    ttk.Label(dialog, text="No configuration found!").pack()
    buttons_frame = tk.Frame(dialog)
    buttons_frame.pack()
    ttk.Button(buttons_frame, text="Create", command=lambda: dialog_interaction_handler.interact("create", True, additional_action=dialog.destroy)).grid(column=0, row=0)
    ttk.Button(buttons_frame, text="Quit", command=lambda: dialog_interaction_handler.interact("create", False, additional_action=dialog.destroy)).grid(column=1, row=0)
    dialog.resizable(0,0)
    dialog.mainloop()

    if dialog_interaction_handler.get_result("create"):
        try:
            config_file = open(config_file_path, "w")
            config_file.write(json.dumps(default_configuration))
            config_file.close()
        except:
            warn("Failed to save initial config file.", is_exception=True)
            dialog = tk.Tk()
            dialog.title("Failed to save initial config file")
            ttk.Label(dialog, text="Failed to save the initial config file.\n" +
                            "The IDE can still start up, but it is likely that all changes to the configuration will be lost where they would be saved otherwise.").pack()
            ttk.Button(dialog, text="Continue", command=dialog.destroy).pack()
            dialog.resizable(0,0)
            dialog.mainloop()
    else:
        error("No config present and user chose not to create one. Exiting.", is_exception=False, handle_gracefully=True)
        # exit with success exit code anyway because this is not a program failure
        sys.exit(EXIT_SUCCESS)

################################################################################
# PROGRAM MAIN WINDOW
################################################################################

main_window = tk.Tk()
main_window.title("IDE")
main_window.geometry(get_configuration_value("window geometry"))

def not_implemented():
    warn("Not implemented!")

# format:
#   "":{} -> menu or submenu
#   "":function -> menu entry
#   "":None -> disabled menu entry
#   None:None -> separator
#
# Entries with ... at the end are supposed to open dialogs whereas entries without dots are supposed to take effect immediately
menu_structure = {
    "IDE": {
        "Preferences...": not_implemented,
        "Quit": not_implemented
    },
    "Project": {
        "New": {
            "No known project types": None
        },
        "Open...": not_implemented,
        "Close": {
            "No open projects": None
        },
        None: None,
        "Preferences...": not_implemented,
        "Search...": not_implemented,
        "Build": not_implemented
    },
    "File": {
        "New...": not_implemented,
        "Open...": not_implemented,
        "Save": not_implemented,
        "Close": not_implemented,
        None: None,
        "Rename...": not_implemented,
        "Move...": not_implemented,
        "View in File Explorer...": not_implemented
    },
    "Edit": {
        "Cut": not_implemented,
        "Copy": not_implemented,
        "Paste": not_implemented,
        None: None,
        "Search and Replace...": not_implemented,
        None: None,
        "Format": not_implemented,
        "Indent": not_implemented,
        "Unindent": not_implemented,
        "Toggle Comment": not_implemented
    },
    "View": {
        "Zoom in": not_implemented,
        "Zoom out": not_implemented,
        "Normal Size": not_implemented
    },
    "Help": {
        "Manual...": not_implemented,
        "About IDE...": not_implemented,
    }
}

menubar = None
def build_menu(structure_dict, menu):
    for entry in structure_dict:
        if structure_dict[entry]==None:
            if entry==None:
                menu.add_separator()
            else:
                menu.add_command(label=entry)
                menu.entryconfig(entry, state="disabled")
        if isinstance(structure_dict[entry], dict):
            submenu = tk.Menu(menu, tearoff=False)
            build_menu(structure_dict[entry], submenu)
            menu.add_cascade(label=entry, menu=submenu)
        if callable(structure_dict[entry]):
            menu.add_command(label=entry, command=structure_dict[entry])

def rebuild_menu():
    menubar = tk.Menu(main_window)
    build_menu(menu_structure, menubar)
    main_window.config(menu=menubar)

rebuild_menu()

def handle_exit():
    set_configuration_value("window geometry", main_window.geometry())
    main_window.destroy()

main_window.protocol("WM_DELETE_WINDOW", handle_exit)
main_window.mainloop()